The invention concerns an encapsulated component with a reduced overall height, in particular a component working with acoustic waves which is constructed on a piezoelectric substrate.
In electrical components, the trend increasingly goes towards components without massive housings. In order to nevertheless protect the components from environmental influences, various methods have already been proposed for simple encapsulation of the components. One possibility is to completely provide a component with a protective layer, for example to completely embed it in plastic, whereby only the electrical connections for the component are free of plastic. However, such an encapsulation is problematic for components that bear component structures on a surface that are sensitive to a direct embedding.
For example, for surface wave components it has already been proposed to cover the component structures arranged on the surface of a piezoelectric substrate with the aid of a simple cap, in particular a cap of plastic, before the component is further encapsulated. Such an encapsulation method used by the applicant under the name PROTEC and such an encapsulation method is, for example, known from EP 0 759 231 B1. Since such an integrated, producible cap for the component structures itself provides only a slight protection, it was, for example, proposed in DE 198 06 818 A to solder the component on a carrier in a flip-chip arrangement, and subsequently to cover it with a foil that seals tight with the carrier between the components. In further variations of such foil coverings of components, it is also proposed to further hermetically seal these foils via application of a metal layer over the foil and to, for example, galvanically reinforce this metallization. However, what is disadvantageous in this method is the elaborate lamination process for application of the foil as well as the wet-chemical or, respectively, galvanic metallization that can, given slight leakages of the foil covering, already lead to a penetration of moisture into the component structures.